Fluid sampling pumps have long been used to take repeated samples from a pipe line or other vessel, and incrementally input sample "bites" into a storage cylinder or similar container, so that the fluid in the cylinder represents a test fluid for determining the characteristics of the fluid stored in the vessel or flowing through the pipe line. The pipe line conventionally includes a threaded side port for sealingly mounting a valve assembly thereto, with a probe extending from the valve assembly into the pipe line for transmitting a sample to the pump. The sampling pump, a pump actuator, a regulator, and an electronic sampling controller are typically housed within a protective housing. Customers of sampling systems prefer a mounting technique whereby the sampling pump and related components within the housing may be mounted directly to the pipe line, thereby reducing installation costs. Various types of liquid or gas sampling pumps, and further background information regarding systems for obtaining fluid samples, are disclosed in U.S. Pat. Nos. 4,172,670, 4,403,518, 4,470,773, 4,525,127, 4,531,895, 4,557,151, 4,628,750 and 5,074,154.
Some prior art sampling pump systems have been connected by flexible tubing or similar flexible conduits to the pipe line, and the sampling pump and enclosure are then not physically supported by the pipe line. Those skilled in the art appreciate that fluid being transmitted in a hot loop from a pipe line to a sampling pump may be under an extremely high pressure, e.g., in excess of 1,500 PSI. Flexible lines which interconnect components and reliably transmit such high pressure fluids are expensive, and are thus generally avoided. When using either flexible tubing or rigid pipe to form the flow lines between the pipe line and the sampling pump, the sampling pump, its enclosure and the related components may be supported by a pedestal or other structure separate from the pipe line, or alternatively may be supported by arms or mounting brackets to the pipe line. The sampling pump system user generally desires to support the sampling pump and enclosure from components which both structurally interconnect the sampling pump to the pipe line and which serve to transmit the fluid from the pipe line to the sampling pump, thereby reducing installation costs. Such users also prefer that the flow line and mounting system have the capability to allow the user to remount an existing conventional pump and enclosure at a new installation site according to the preferred supporting techniques, and without disconnecting the pump or the related equipment within the enclosure in order to remount the pump and enclosure according to this preferred technique to the same or a new pipe line.
Operators of sampling pumps generally prefer to maintain a "hot loop" between the pipe line and the sampling pump. This hot loop allows a slight amount of fluid to flow substantially continuously from the pipe line to a location adjacent the inlet port of the pump, so that the pump is sampling fluid highly representative of fluid flowing through the pipe line at the moment the sample is taken. In a hot loop system, fluid which is not incrementally sampled by the pump is returned to the pipe line. This hot loop system typically employs a manifold block at the base of the pump, with the manifold block being housed within the enclosure and including a pair of ports for fluid communication with the hot loop flow lines. The methods and apparatus of this invention are of the type which desirably provide this hot loop system between the sampling pump and the pipe line to maintain high accuracy for the sampling technique. The present invention is concerned with improved techniques for mounting the sampling pump and relating components to the pipe line, and with techniques which provide both the hot loop flow lines and the structural connection between the pipe line and the sampling pump, while accomplishing these goals in a cost effective manner.
U.S. Pat. No. 4,928,536 discloses a sampling system with a lower body 13 for structurally interconnecting a pump with a pipe line. The mounting system is not adapted for engagement with a conventional sampling pump manifold, is expensive to manufacture, and when installed required modifications to a conventional sampling pump enclosure and/or adaption to the components within the enclosure. U.S. Pat. No. 4,391,152 discloses a complex sampling system which includes a plurality of ball valves, and also is not readily adaptable to standard sampling pump systems with conventional enclosures. The system disclosed in this patent does not provide the desired hot loop path as discussed above, and is apparently supported from a structure independent of the pipe line. U.S. Pat. No. 3,625,065 discloses a sampling system which utilizes flow lines between the sensor and the pipe line, with the flow lines being of a type which cannot reasonably support sampling pumps and related components within the enclosure, as discussed above. U.S. Pat. No. 3,534,613 discloses an early version of sampling system which does not form a reliable seal with the pipe line. Flow passes through flexible tubular member 67, and the system is not the hot-loop type. U.S. Pat. No. 3,007,340 discloses an electrical measurements system with valves 23 and 28 being in fluid communication by the conduit 24. U.S. Pat. No. 2,351,764 discloses a gas sampling system with external pipes and valves for interconnecting ports.
U.S. Pat. No. 5,109,709 discloses a system for mounting a sampling pump and related components within an enclosure to a pipe line while transmitting fluid in a hot loop between the pipe line and the sampling pump. The technique of this patent permits the mounting of the sampling pump and enclosure at one of a plurality of rotational positions, so that the installer may selectively rotate the pump and enclosure with respect to the pipe line when making the interconnection. The plurality of fittings, nipples, and an interface plate connect the valve body fixed to the pipe line and the pump manifold, while transmitting fluid to the pump in the desired hot loop. The technique disclosed in this patent, while highly reliable, is cost prohibitive for many applications due to the machining expense of the fittings, nipples, and interface plate. Moreover, the system disclosed in this patent includes numerous components to provide the desired structural and fluid connection between the pump and the pipe line, and is considered too complex by some sampling pump system users.
U.S. Pat. No. 4,920,626 discloses a device for structurally interconnecting a instrument manifold within an orifice plate assembly. U.S. Pat. No. 4,942,772 discloses a stack sampling system utilizing sampling lines between sampling equipment and a fitting threaded to the stack. U.S. Pat. No. 4,858,477 discloses a flow system for a dry material sample collector. The techniques disclosed in these patents illustrate efforts of companies involved in sampling technology, but do not teach the improved sampling pump mounting technique of the present invention.
The disadvantages of the prior art are overcome by the present invention, and improved methods and apparatus are hereafter disclosed for mounting a sampling pump and related components to the fluid source, such as a pipe line. The mounting technique of the present invention maintains high reliability for the sampling procedure by utilizing a hot-loop flow technique, allows the sampling system user to the reliably install the sampling pump at a desired location without utilizing special tools or specially adapted mounting components, minimizes installation costs, and may be used to re-mount existing sampling pump systems at the same or new installation sites.